The present invention relates to a slip ring or commutator motor having at least one brush held on the stator side. The brush is pressed, by a brush compression spring, against the surface of a slip ring or commutator. The brush is pivotable about an axis parallel to the direction of the commutator axis or slip ring axis.
Such a motor is disclosed in DE-PS 548,073. In the conventional motor mentioned above, to better adapt the carbon brush to deviations in the circularity of the sliding surface of the commutator or the slip ring, the carbon brush is supported in a brush guiding box. On opposite sides of the brush guiding box, there are fitted projections having outwardly directed surfaces belonging to a common partial cylindrical surface. Corresponding contact surfaces, likewise associated with a common cylindrical surface, are provided on a retaining arm holding the brush box such that the brush can adjust itself in a suitable direction to deviations from circularity of the sliding surface of the commutator or the slip ring. The cylindrical surfaces roll on one another.
A double brush holder is disclosed in CH-A-334,086 where two brushes are each held guided in a brush box. The two brush boxes are connected by means of a cross bar. An axle originates from the cross bar. This axle has a brush compression spring with an eye at its one end plugged into it. The other end of the brush compression is wound in an elastic manner onto a cylinder with a cylinder axle. The free ends of the cylinder axle project from both end faces of the cylinder and abut, via rollers, the head ends of the brushes (i.e., the surface facing away from the commutator). The complete module, with brush box, cross bar and brush compression spring suspension, is retained on the motor side such that a brush supporting arm engages on an external wall of a brush box.